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Finding the Fourth Proportional to 280.87, 421.33 and 85.89

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Solution

The fourth proportional to 280.87, 421.33 and 85.89 is: 128.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.87 : 421.33 = 85.89 : x
  2. Step 2: Convert to fraction form
    280.87/421.33 = 85.89/x
  3. Step 3: Cross multiply
    280.87x = 421.33 × 85.89
  4. Step 4: Simplify right side
    280.87x = 36,188.03
  5. Step 5: Solve for x
    x = 36,188.03/280.87
  6. Step 6: Final answer
    x = 128.84

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.